Climatic Region and Vine Structure: Effect on Pinotage Wine … · 2006. 12. 19. · Climatic Region and Vine Structure: Effect on Pinotage Wine Phenolic Composition, Total Antioxidant

Climatic Region and Vine Structure: Effect on Pinotage Wine PhenolicComposition, Total Antioxidant Capacity and Colour*

D. de Beer1, E. Joubert1'2' , J. Marais2, D. van Schalkwyk2 and M. Manley1

(1) Department of Food Science, Stellenbosch University, Private Bag XI, 7602 Matieland (Stellenbosch), South Africa;[email protected], [email protected]

(2) ARC Infruitec-Nietvoorbij (Fruit, Vine and Wine Institute of the Agricultural Research Council), Private Bag X5026, 7599Stellenbosch, South Africa; [email protected], [email protected], [email protected]

Submitted for publication: April 2006

Accepted for publication: June 2006

Key words: Antioxidants, climatic region, free radical scavenging, phenolic compounds, vine structure.

The phenolic composition, total antioxidant capacity (TAC) and colour of Pinotage wines of the 2001,2002 and 2003vintages were investigated, using spectrophotometric, high-performance liquid chromatography (HPLC), freeradical scavenging and objective colour analyses. Grapes were harvested from grapevines in three climatic regionsranging from cool to warm, with bush (20- and 30-cm trunk height) and trellised (30- and 60-cm trunk heights) vinetreatments, on several vineyard sites in each climatic area. Climatic region had a significant effect on the contentof several phenolic compounds; the concentration of anthocyanin monoglucosides, flavonols, flavan-3-ols andtartaric acid esters of hydroxycinnamic acids generally increased as the climatic region becomes cooler, whileconcentrations of acylated derivatives and free hydroxycinnamic acids decreased. Wines made from bush vinescontained higher concentrations of flavonols, gallic acid and flavan-3-ols than those from trellised vines, but lowerconcentrations of some anthocyanin monoglucosides and acylated derivatives, as well as non-coloured polymers.These trends resulted in differences in TAC and objective colour parameters, although the different vintages didnot show the same trends in all cases. More vintages should therefore be investigated to clarify these effects. Winesfrom the cool climatic regions and from bush vines were generally darker coloured, with higher TAC than thosefrom the warm climatic regions and bush vines, respectively. High TAC, therefore, coincided with higher colourquality. Variations in TAC were partly explained by trends for individual phenolic compounds, although unknowncompounds played a major role.

INTRODUCTION

Grape phenolic composition is greatly affected by climatic con-ditions and vine management practices (Jackson & Lombard,1993). A wide variety of systems have been developed to describethe viticultural potential of a climatic region (inter alia, Amerine& Winkler, 1944; Smart & Dry, 1980; Huglin, 1986). In the SouthAfrican context, the Western Cape viticultural regions have beendivided by Le Roux (1974) according to the heat summationmodel of Amerine & Winkler (1944), as well as by De Villiers etal. (1996), according to the mean temperature of the warmestmonth model of Smart & Dry (1980), using the mean Februarytemperatures. High temperatures have been reported to result inlower anthocyanin (Kliewer, 1970; Bergqvist et al, 2001; Spaydet al, 2002) and total phenol (Bergqvist et al, 2001) berry con-tent compared to lower temperatures.

Vine management practices modify the canopy microclimate inorder to control sunlight exposure and fruit temperature duringberry maturation. Sunlight exposure generally results in higher juicepH, total soluble solids, anthocyanin, flavonol and phenolic con-tents, while titratable acidity, malate content, and berry mass arelower (Kliewer, 1970; Crippen & Morrison, 1986; Reynolds et al,

1986; Spayd et al, 2002; Downey et al, 2004). In warm climates,however, a high degree of sunlight exposure negatively affects theanthocyanin content of red grapes (Haselgrove et al, 2000).

Generally, Pinotage vines grown in South Africa are head-trained and spur-pruned (bush vines), or trained to a bilateral hor-izontal cordon and spur-pruned with upward vertical shoot posi-tioning (trellised vines). Winemakers and producers speculatewhether bush vines or trellised vines are preferable for makinghigh-quality Pinotage wines. Vine structure was demonstrated toaffect the phenolic composition of berry skins (Tamborra et al.,2003). It is also not clear whether cultivation of Pinotage undercool or warm climatic conditions is best for obtaining high qual-ity wine. It is expected that these factors will also affect theantioxidant capacity of Pinotage wines. No research to show theeffect of climatic region or vine management practices on theantioxidant capacity of red wines has been reported.Consequently, the aim of this project was to determine the effectof vine structure (training system and trunk height), as well as cli-matic region, on the phenolic composition, total antioxidantcapacity (TAC) and colour of Pinotage wines from the WesternCape.

* Part of work submitted for a PhD in Food Science at Stellenbosch University, 2006.

** Corresponding author: [email protected],

Acknowledgements: Andre Schmidt is thanked for technical assistance. Winetech, the National Research Foundation (NRF) and the Technology and Human Resources forIndustry Programme (THRIP) are thanked for financial support. Frikkie Calitz of the Biometry Unit, ARC Infruitec-Nietvoorbij, is thanked for statistical analysis of data.

S. Afr. J. Enol. Vitic, Vol. 27, No. 2, 2006

151

152 Effect of climatic region and vine structure on Pinotage wine composition.

MATERIALS AND METHODS

Viticultural treatments and wine-making procedure

Vineyard sites were located in three climatic regions of thecoastal region (Western Cape, South Africa), differentiated ac-cording to average February temperatures using macro climaticweather station data, as described by De Villiers et al. (1996) (seeFig. 1): region II (av February temperature = 19.0 - 20.9°C),region III (av February temperature = 21.0 - 22.9°C) and regionIV (av February temperature = 23.0 - 24.9°C). Temperature datataken during February 2004 and 2005 using mini data loggers(Tinytag Plus TGP-1500, Gemini Data Loggers (UK) Ltd.,Chichester, UK) at individual vineyards were used to confirm theallocation of vineyard sites on the border between regions to aspecific region (data not shown). The seven vineyard sites in cli-matic region II were located in the Darling (1 site), Stellenbosch(higher than 300-m above sea level) (5 sites) and Hemel andAarde Valley (Hermanus) (1 site) regions. In climatic region IIIthe six vineyard sites were located in the Kuils River (2 sites) andStellenbosch (lower than 300-m above sea level) (4 sites) regions.In climatic region IV the experimental sites were located in theDarling (1 site), Riebeeck-Wes (1 site) and Wellington/Paarl (5sites) regions. All vines were Pinotage clone PI 48 grafted onto99 Richter rootstock. Vine distances, row orientation, cover crop,nutrition and irrigation were not standardised as sites had toreflect normal viticultural practices in a region. Vine structuretreatments were bush (head-trained and spur-pruned) and trellised(trained to a bilateral horizontal cordon and spur-pruned withupward vertical shoot positioning) vines with main trunk heightsof 20 or 30 cm for bush vines and 30 or 60 cm for trellised vines.Canopy management was applied for all vines, namely suckeringto two bearer shoots per bearer, suckering between bearers andleaf removal at berry set to three-leaf layers to obtain an optimalcanopy density (Smart & Robinson, 1991; Hunter, 1999). Allcombinations of these treatments were carried out on each of thevineyard sites during the 2000/2001, 2001/2002 and 2002/2003growing seasons.

The sugar content of the grapes, when harvested, rangedbetween 24 and 26°B, with 14%, 14% and 16% of the treatmentsharvested outside of this range during 2001, 2002 and 2003,respectively. Harvesting was performed manually by the samepickers at each site. Different vineyard sites in the same climaticregion represented repetitions. Wines were produced with 20 to30 kg of grapes per treatment at the experimental cellar of ARCInfruitec-Nietvoorbij (South Africa) according to the basic wine-making protocol with no wood contact (described in De Beer etal, 2006). After bottling, the wines were stored at 15°C. Eightmonths after production, aliquots of each wine were frozen at -20°C to prevent further phenolic changes until analyses could becarried out. Samples were analysed immediately after defrosting.

Chemicals and phenolic reference standards

2,2'-Azino-di-(3-ethylbenzo-thialozine-sulphonic acid) (ABTS)was obtained from Boehringer Mannheim GmbH (Mannheim,Germany) and high-performance liquid chromatography (HPLC)grade acetonitrile and glacial acetic acid from Riedel-de Haen(Seelze, Germany). Phosphoric acid (HPLC grade) and 4-dimethy-lamino-cinnamaldehyde (DAC) were obtained from Fluka (Buchs,Switzerland) and Folin-Ciocalteau's phenol reagent from Merck

(Darmstadt, Germany). Potassium persulphate (K2S2O8) wasobtained from Sigma Chemical Co. (St. Louis, MO, USA) and 6-hydroxy-2,5,7,8-tetra-methylchroman-2-carboxylic acid (Trolox)from Aldrich Chemical Co. (Gillingham, UK). Methanol (AR),concentrated hydrochloric acid (AR), sodium chloride (AnalAR)and sodium hydroxide (AnalAR) were obtained from SaarChem(Midrand, South Africa). Phenolic reference standards includedgallic acid, (+)-catechin and quercetin-3-rhamnoside (Q-3-Rham)from Sigma; caffeoyltartaric acid from Chromadex (Santa Ana,CA, USA); caffeic acid, quercetin and kaempferol from Fluka; pro-cyanidin Bl, quercetin-3-Glc and myricetin from Extrasynthese(Genay, France); and delphinidin-3-Glc, peonidin-3-Glc, petuni-din-3-Glc and malvidin-3-Glc from Polyphenols AS (Sandnes,Norway). Water used in the experiments was purified and de-ionised with a Modulab water purification system (Separations,Cape Town, South Africa), except for preparation of HPLC mobilephases where de-ionised water was further treated using a Milli-Qacademic water purifier (Millipore, Bedford, MA, USA).

Spectrophotometric analysis of phenolic composition

Pinotage wines from all vintages were subjected to spectrophoto-metric analysis of the major phenolic groups described below.

The total phenol content of wines was determined using themethod of Singleton and Rossi (1965), scaled down to a finalreaction volume of 5 mL. Gallic acid was used as standard andresults were expressed as mg gallic acid equivalents/L.

The anthocyanin content of wines was estimated using the pHshift method of Ribereau-Gayon & Stonestreet (1965), adaptedby De Beer et al. (2003). A pH 4.9 buffer was used instead of apH 3.5 buffer. Anthocyanins were quantified as mg malvidin-3-glucoside equivalents/L.

The total flavan-3-ol content (DAC) of wines was measuredusing the method of McMurrough & McDowell (1978), as adapt-ed by de Beer et al. (2003). (+)-Catechin was used as a standardand the results expressed as mg catechin equivalents/L.

Spectrophotometric measurements were made in disposablepolystyrene 2.5-mL macro cuvettes with 1-cm path length usinga Beckman DU-65 UV/Vis spectrophotometer (BeckmanInstruments Inc., Fullerton, CA, USA).

HPLC analysis of phenolic composition

Individual phenolic compounds, as well as coloured and non-coloured polymers detected at 520 and 280 nm, respectively, inPinotage wines from the 2002 and 2003 vintages were quantifiedusing an HPLC method (Peng et al, 2002), modified as describedby De Beer et al. (2006). Polymers included polymeric phenoliccompounds with five or more subunits consisting of anthocyaninsand flavan-3-ols for coloured polymers and only flavan-3-ols fornon-coloured polymers. The HPLC apparatus used was a WatersLC Module I equipped with a Waters 2996 photodiode arraydetector using Millenium32 version 4.0 software (Waters, Milford,MA, USA). Separation was achieved on a PolymerX column (250x 4.6 mm, 100 A pore size, 5-um particle size) from Phenomenex(Torrance, CA, USA). A PRP1 guard cartridge (20 x 2.3 mm)packed with a similar material (Hamilton, Reno, NV, USA) and aPEEK PAT frit (5 mm) were used to protect the analytical column.Wines were filtered using 0.45-|jm Millex-HV hydrophilic PVDF33-mm syringe-tip filter devices (Millipore) before automatedduplicate injections of 20 uL each. The column was held at 30°C


Effect of climatic region and vine structure on Pinotage wine composition. 153

Compiled by Arc Infruitec-Nietvoorbijand Department of Agriculture : Western CapeCopyright reserved 10

Hsrmanus

0 10 Kilometers

FIGURE 1

Division of Western Cape Pinotage cultivation areas into climatic regions on the basis of mean February temperatures (MFT) as described by De Villiers et al. (1996)[triangles indicate experimental vineyard sites].

during the run and the flow-rate was 0.9 mL/min. The mobilephases used were: 1.5% (v/v) aqueous phosphoric acid (A) and1.5% (v/v) phosphoric acid in acetonitrile/water (80/20) (B).

ABTS radical cation scavenging assay

The total antioxidant capacity (TAC) of Pinotage wines from allvintages was measured (TACM) using the ABTS'

+ scavengingassay (Re et ah, 1999). The content of individual phenolic com-pounds as measured using HPLC and their experimental Troloxequivalent antioxidant capacity (TEAC) values (reported in DeBeer et al., 2006) were used to calculate the theoretical TAC(TACCAL). The remaining TAC (TACR) is the difference betweenTACM and TACCAL- Analysis and calculations were carried out asdescribed by De Beer et al. (2006).

Objective colour parameters

A Colorgard System 2000 Colorimeter (BYK-Gardner,Geretsried, Germany) was used to obtain the objective colourparameters of the undiluted Pinotage wines from all vintages intransmittance mode with a 5-mm fixed path length optical cell.The colorimeter was calibrated before use with a non-diffusingblack reflectance standard (BYK-Gardner, Geretsried, Germany)to obtain a zero calibration. Objective colour measurements were

taken less than one hour after opening of a wine bottle to min-imise colour changes. The CIELab parameters, namely a*(red/green chromaticity), b* (yellow/blue chromaticity) and L*(lightness), were measured using the CIE 1931 standard colon-metric observer under illuminant C (geometry is 45° illuminationand 0° viewing). The h* (hue angle; °) and C* (chroma) were cal-culated as follows:

h* = tan1 (b*/a*)

C* = [(a*)2 + (b*)2]m

Names for hues were adapted from Gonnet (1999) based on theh* values. Hue angle values of 0°, 7.5°, 15°, 22.5°, 30°, 37.5° and45° correspond to magenta, red-magenta, magenta-red, red,orange-red, red-orange and orange, respectively.

Statistical analysis

Analysis of variance was performed on the means for climaticregions and vine structure treatments to determine whether sig-nificant differences occurred. The Student J-LSD test (P < 0.05)was used to determine the statistical differences between means.Covariance analysis was also performed with grape sugar content(°B) as covariate. Analysis of variance, difference testing andcovariance analysis were done using the SAS version 8 software



package (SAS Institute Inc., Cary, NC). In cases where thecovariate had a significant (P < 0.05) effect, the adjusted meanswere compared. Where no interactions between different factorswere observed, or where treatments did not differ significantly,data were pooled. Canonical discriminant analysis of dataobtained for wines produced during 2002 and 2003, using for-ward stepwise variable selection, was performed to distinguishbetween climatic regions and vine structure treatments. Pearsonproduct moment correlation coefficients between parameters andtheir P-values were calculated. Canonical discriminant analysisand calculation of correlation coefficients were done using theSTATISTICA 6 software package (StatSoft, Inc., Tulsa, OK).

RESULTS

The average grape sugar content did not differ significantlybetween the vintages (Table 1).

Vintage-related variations

Some vintage-related variations were observed in terms of thephenolic composition and TAC of Pinotage wines (Tables 1 & 2).The climatic region and vine structure treatments had varyingeffects depending on vintage.

Spectrophotometric determination of phenolic content showedsignificant differences between wines from different vintages(Table 1). Wines of the 2001 vintage had the highest total phenolcontent, as well as the highest monomeric, polymeric and totalanthocyanin content (pH shift). The 2002 wines had the lowestpolymeric and total anthocyanin content (pH shift), while the2003 wines had the lowest total flavan-3-ol content (DAC).

Only the individual phenolic compounds for the 2002 and 2003wines were quantified (Table 2). Some flavonol compounds,

namely quercetin-3-galactoside (Gal), myricetin, kaempferol andisorhamnetin, were only detected in some wines. Of the 63 winesproduced during 2002, measurable amounts of quercetin-3-Gal,kaempferol and isorhamnetin were present in 18, 38 and 47wines, respectively, while of the 77 wines produced in 2003 mea-surable amounts of quercetin-3-Gal, myricetin and isorhamnetinwere present in 23, 25 and 36 wines, respectively. Values for thesecompounds in the respective vintages will not be reported, as sta-tistical analysis was not possible. The total flavonol content, how-ever, refers to the sum of all flavonols.

Large vintage-related variations were found for the contents ofindividual phenolic compounds (Table 2). The 2002 wines hadsignificantly higher concentrations of most phenolic compoundscompared to the 2003 wines, except for vitisin A, malvidin-3-/?-coumaroylglucoside (Glc-Coum), quercetin-3-Glc, gallic acid,caftaric acid and non-coloured polymers, which did not differ sig-nificantly, and malvidin-3-Glc, peonidin-3-Glc-Ac, malvidin-3-Glc-Ac, coloured polymer (HPLC), an unknown flavonol andquercetin-3-rhamnoside (Rham), which were significantly lower.

The TAC of the wines varied significantly between vintages,with the TACM highest during 2002 and lowest during 2001(Table 1). The TACCAL and TACR were lower for the 2003 winesthan the 2002 wines.

For each vintage, the total phenol content correlated well(P < 0.001) with the TACM values of the wines of that particularvintage, while a weaker, but still significant correlation(P < 0.001) was observed when data of the three vintages werepooled (Fig. 2 and Table 3). Similar trends were observed for thecorrelations (P < 0.001) between the total flavan-3-ol content(DAC) and the TACM values for the different vintages, although

TABLE 1

Vintage-related variation in sugar content of grapes, as well as the phenolic composition (measured spectrophotometrically), antioxidantcapacity and objective colour parameters of the 2001, 2002 and 2003 Pinotage wines.

25.0 ac(± 0.1 )a

2347.1 a (±57.6)

494.3 a (± 8.2)

130.6 a (± 3.4)

624.9 a (±11.0)

153.2 a (± 5.2)

11.84 c (±0.28)

na

na

59.88 b (± 0.36)

14.05 a (± 0.28)

29.16 b (±0.87)

58.03 b (± 0.32)

14.58 a (± 0.34)

24.9 a (±0.1)

1743.2 c (± 32.2)

443.5 b (±7.4)

54.1 c(±1.5)

497.5 c (± 8.4)

144.1 a (±4.3)

14.87 a (± 0.28)

2.13 a (±0.03)

12.84 a (± 0.27)

61.81 a (±0.33)

14.09 a (± 0.36)

33.07 a (± 0.72)

59.87 a (± 0.29)

15.08 a (± 0.41)

25.0 a (±0.1)

1879.4 b (±32.9)

462.5 b (± 7.4)

64.7 b (± 2.0)

527.2 b (± 9.2)

182.6 b (±3.4)

13.36 b (± 0.24)

1.97 b (±0.02)

11.35 b (±0.23)

60.75 b (± 0.40)

13.62 a (± 0.27)

31.94 a (±0.72)

59.30 a (± 0.23)

14.38 a (± 0.33)

a means taken over all climatic regions and vine structure treatments for a specific vintage; b °B; c different letters in a row denote significant differences (P < 0.05); d stan-dard error of mean; e mg gallic acid equivalents/L; f mg malvidin-3-glucoside equivalents/L; s mg (+)-catechin equivalents/L; h total antioxidant capacity in mM Troloxequivalents as measured;' total antioxidant capacity in mM Trolox equivalents as calculated from the content of monomeric phenolic compounds and their Trolox equiv-alent antioxidant capacity; J TACR = TACM - TACCAL; k chroma;' hue angle (°); m lightness; n red/green chromaticity; ° yellow/blue chromaticity; na = not available.



TABLE 2

Vintage-related variation in phenolic composition11 (measured byHPLC) of the 2002 and 2003 Pinotage wines.

Compound/Phenolic group 2002 2003

TABLE 3

Correlations between phenolic group content and total antioxi-dant capacity of the 2001, 2002 and 2003 Pinotage wines.

Anthocyanins

Delphinidin-3-Glc

Petunidin-3-Glc

Peonidin-3-Glc

Malvidin-3-Glc

Delphinidin-3-Glc-Acd

Vitisin Ad

Petunidin-3-Glc-Acd

Peonidin-3-Glc-Acd

Malvidin-3-Glc-Acd

Malvidin-3-Glc-Coumd

Total monomeric anthocyanins6

Coloured polymersf

Flavonols

Unknown flavonolg

Quercetin-3-Gal

Quercetin-3-Glc

Quercetin-3-Rham

Myricetin

Quercetin

Kaempferol

Isorhamnetin

Total flavonolsf

Phenolic acids

Gallic acid

Caftaric acid

Caffeic acid

Coutaric acid1

p-Coumaric acid

Total phenolic acidsf

Flavan-3-oIs

(+)-Catechin

Procyanidin B1

Non-coloured polymers1

Total monomersk

16.82 ab (± 0.60)c

24.30 a (± 0.60)

9.70 a (± 0.39)

211.21b (±4.30)

6.20 a (±0.18)

6.29 a (± 0.38)

6.26 a (±0.17)

4.07 b (±0.14)

49.47 b(± 1.50)

20.78 a (± 0.86)

355.12 b (±6.74)

8.21 b (± 0.47)

18.96 b (±0.89)

data not shown11

13.65 a (± 0.49)

8.31b (±0.27)

3.25 (±0.18)

4.38 a (± 0.30)

data not shownh

data not shownh

50.54 a (±1.91)

12.75 a (± 0.66)

180.78 a (± 4.49)

5.60 a (± 0.21)

18.45 a (±0.52)

2.10 a (±0.14)

219.69 a (± 4.92)

13.50 b (±0.54)

21.21b (±0.58)

5.71b (±0.32)

228.88 a (± 3.10)

4.59 b (±0.18)

5.30 a (± 0.39)

5.15 b (±0.35)

6.04 a (±0.17)

67.61 a (± 1.47)

21.48 a (±0.79)

379.46 a (±5.11)

13.96 a (± 0.43)

24.64 a (± 0.99)

data not shown11

14.70 a (± 0.75)

9.25 a (± 0.29)

data not shownh

3.37 b (±0.14)

0.67 (± 0.05)

data not shown11

53.78 a (± 1.99)

11.27 a (±0.63)

175.92 a (± 3.22)

0.84 b (± 0.08)

16.08 b (± 0.29)

1.40 b (±0.10)

205.51b (±3.51)

22.63 a (± 0.74) 8.95 b (± 0.26)

32.04 a (±1.13) 13.01 b (± 0.26)

119.77 a (±5.30) 125.17 a (± 6.03)

680.01 a (± 10.02) 660.71 a (± 6.13)

a mg/L unless otherwise noted and means taken over all climatic regions and vinestructure treatments for a specific vintage; b different letters in a row denote sig-nificant differences (P < 0.05); c standard error of mean; d mg correspondinganthocyanin-3-Glc equivalents/L; e mg malvidin-3-Glc equivalents/L; f sum ofphenolic group content; g mg rutin equivalents/L; h data not shown due to largenumber of wines without detectable amounts of compound;' mg p-coumaric acidequivalents/L; J mg (+)-catechin equivalents/L; k sum of all quantified monomer-ic phenolic compounds; Gal = galactoside; Glc-Coum = p-coumaroylglucoside;Rham = rhamnoside.

the correlation for the pooled flavan-3-ol content (DAC) of allthree vintages with the TACM was better than for the total phenolcontent. A very weak correlation (P < 0.05) was observed for thetotal monomer content (HPLC) with the TACM when data of the2003 vintage were considered, where no correlation (P > 0.05)was obtained for the 2002 data, although when data of the 2002and 2003 vintages were pooled, a weak, but significant (P <0.001) correlation was observed. The TACM had a significant

Phenolic group All vintages(pooled)

2001 2002 2003

Spectrophotometric assay

Total phenolsa

Total anthocyanins (pH shift)c

Total flavan-3-ols (DAC)d

HPLC

Total monomerse

Total anthocyaninsf

Total flavonolsf

Total phenolic acidsf

0.361b ** 0.958 **

0.131 ns 0.633**

0.650 ** 0.926**

0.271

-0.315

0.325

0.497

0.885** 0.910:

0.285 * 0.633:

0.819 ** 0.892 ;

0.242 ns 0.236

-0.240 ns -0.262

0.430 ** 0.363 :

0.429 ** 0.506 ;

a mg gallic acid equivalents/L; b correlation coefficient for correlation betweenphenolic group and the total antioxidant capacity; c mg malvidin-3-glucosideequivalents/L; d mg (+)-catechin equivalents/L; e sum of all quantified monomer-ic phenolic compounds; f sum of phenolic group content; na = not available.

moderate positive correlation (P < 0.001) with the total antho-cyanin content (pH shift) of the 2001 and 2003 vintages only,while the 2002 vintage showed a weak, but significant positivecorrelation (P < 0.05). On the other hand, the monomeric antho-cyanin content (HPLC) showed weak negative correlations(P < 0.05) for the pooled data of the 2002 and 2003 vintages, aswell as for the 2003 data separately. The total phenolic acid andtotal flavonol contents (HPLC) correlated weakly, but significant-ly (P < 0.001), with the TACM when data for the 2002 and 2003vintages were considered separately or pooled.

The objective colour parameters, C*, L* and a*, of the wineswere significantly affected by vintage, but no significant differ-ences were observed for h* and b* (Table 1). The 2002 wines hadhigher C* values, and the 2001 wines lower L* and a* values thanthe wines from other years. A plot of L* values against C* valuesrevealed an interesting phenomenon (Fig. 3). As L* decreased, C*increased up to a point, where after an inversion occurs with a fur-ther decrease in L* corresponding to a decrease in C*. This inver-sion also occurs for both a* and b*.Climatic region x vine structure treatment interaction

Only a small number of interactions between climatic region andvine structure treatment was observed for the wines (Table 4).

During 2002, the climatic region affected the malvidin-3-Glccontent of wines only for the trellised vine treatments, with regionIII wines having a higher content than region II wines (Table 4).Significant differences between wine produced from bush andtrellised vines were only observed for region III, with the trellisedvine treatments resulting in a higher malvidin-3-Glc content com-pared to the bush vine treatments. A similar trend, although notsignificant, was observed for the malvidin-3-Glc content ofregion II and IV wines. The monomeric anthocyanin content(HPLC) during 2002 followed the same trend as the malvidin-3-Glc content.

Different results were obtained for the anthocyanin content ofthe 2003 wines compared to that observed for the 2002 wines(Table 4). The malvidin-3-Glc-Ac content of wines produced


156 Effect of climatic region and vine structure on Pinotagc wine composition.

0 500 1000 1500 2000 2500 3000 3500 4000

Total phenol content (mg gallic acid equivalents/L)

FIGURE 2

Correlation of total phenol content with measured total antioxidant capacity

(TACM) for Pinotage wines.

0 10 20 30 40 50 60L*

FIGURE 3

Cartesian plot of L* values against C* (chroma), a* (red/green) and b* (yellow/blue) values for all Pinotage wines.

from bush vines was lower than that of trellised vines only inregion IV. The trend for climatic region, however, was similar forboth bush and trellised vines, with region IV wines having a sig-nificantly higher content than region II wines. The malvidin-3-Glc-Coum content of the wines produced from bush vines waslower than that from trellised vines for all the climatic regions.Significant differences between climatic regions were obtainedfor trellised vines, with region IV resulting in wines with a high-er content than regions II and III.

For both 2002 and 2003, bush vines in region IV gave wines witha significantly higher p-coumaric acid content compared to trel-lised vines (Table 4). Furthermore, the p-coumaric acid content ofwines from region IV bush vines in 2002 was substantially higherthan that of all the other vintages, climatic region and vine structuretreatment combinations. The overall lowest p-coumaric acid con-tent was observed for wines made from region II bush vines in2003. In the case of trellised vines, the climatic region did not affectthe p-coumaric acid content, irrespective of vintage.

No interactions between climatic region and vine structuretreatment were observed for any of the antioxidant capacity orobjective colour parameters of the wines.

Climatic region: Effect on grape sugar content and phenoliccomposition

The grape sugar content did not differ significantly between cli-matic regions for any of the vintages (Table 5).

In most cases, the climatic region where grapevines were culti-vated had a significant impact on the phenolic composition of thewines as measured by spectrophotometric assays (Table 5). Thiswas confirmed by HPLC analysis of individual phenolic com-pounds (Tables 6 to 8).

The total phenol content of the 2001 wines was lower for winesfrom region IV (warmest) compared to the other regions, whilefor the 2002 vintage the total phenol content of the wines fromthe warmest region was significantly lower than that of region II(coolest) (Table 5). For the 2003 vintage, however, the total phe-nol content of region II and III wines did not differ significantly,but region II wines had a higher total phenol content than regionIV wines.

The monomeric, polymeric and total anthocyanin contents (pHshift) of the wines were lower for the warmest climatic regionduring 2001 compared to the other regions (Table 5). However,these parameters, as well as the monomeric anthocyanin content



TABLE 5

Sugar content of grapes and phenolic composition3 (measured spectrophotometrically) of the 2001, 2002 and 2003 Pinotage wines.

2001: Climatic regionf

Region II

Region HI

Region IV


Region II

Region III

Region IV


Region II

Region III

Region IV

2001: Vine structure treatment1

Bush vines

Trellised vines


Bush vines

Trellised vines

2003: Vine structure treatment'

Bush vines

Trellised vines

Sugarcontentb

25.5 a§ (± 0.2)h

24.8 a (± 0.2)

25.0 a (± 0.2)

24.5 a (± 0.2)

24.5 a (± 0.2)

25.3 a (±0.2)

25.1 a (±0.2)

24.6 a (± 0.2)

25.2 a (± 0.2)

24.9 a (± 0.2)

25.1 a (±0.2)

24.7 a (±0.1)

25.0 a (± 0.3)

25.1 a (±0.2)

24.9 a (± 0.2)

Totalphenols0

2618.0 a (± 134.7)

2578.5 a (± 93.27)

2032.6 b (± 84.0)

1954.6 a (± 70.0)

1771.4 ab (± 65.4)

1586.0 b (± 62.6)

1854.9 ab (± 66.3)

1987.4 a (±77.1)

1777.7 b (±63.1)

2449.1 a (±112.1)

2370.2 a (±113.9)

1812.0 a (± 62.4)

1729.3 a (± 59.2)

1963.6 a (± 56.2)

1783.0 b (± 56.2)

Monomericanthocyaninsd

540.4 a (±21.9)

508.0 a (±15.1)

462.9 b (± 13.6)

452.3 a (± 17.8)

439.3 a (±16.6)

441.9 a (± 15.9)

465.8 a (+ 14.2)

471.7 a (±16.5)

449.3 a (±13.5)

503.5 a (± 15.6)

504.0 a (± 15.9)

441.5 a (±13.3)

447.5 a (± 12.7)

461.0 a (±12.1)

463.5 a (±12.1)

Polymericanthocyaninsd

150.7 a (±7.2)

138.1 a (±5.0)

115.4 b (±4.5)

54.9 a (± 3.6)

53.4 a (± 3.4)

54.2 a (± 3.2)

66.1 ab(± 3.8)

70.2 a (±4.4)

58.1b (±3.6)

136.9 a (±5.9)

132.6 a (± 6.0)

58.2 a (± 2.5)

50.1 b (± 2.3)

66.9 a (± 3.4)

62.7 a (± 3.4)

Totalanthocyaninsd

691.1 a (±27.4)

646.1 a (±19.0)

578.4 b (±17.1)

507.1 a (±20.2)

492.7 a (± 18.9)

496.1 a (±18.0)

532.0 a (± 17.5)

541.9 a (±20.3)

507.4 a (± 16.6)

640.4 a (± 20.6)

636.6 a (±21.0)

499.7 a (±15.1)

497.7 a (± 14.3)

527.9 a (± 15.2)

526.3 a (± 15.2)

Totalflavan-3-o!se

173.8 a (± 12.9)

178.3 a (± 8.9)

122.8 b (±8.1)

172.7 a (± 9.0)

151.3 a (±8.4)

119.9 b (±8.0)

180.6 ab (± 7.5)

197.9 a (± 8.8)

168.5 b (± 7.2)

165.1 a (±10.7)

151.5 a (±10.8)

155.3 a (± 8.2)

140.6 a (± 7.7)

194.8 a (± 6.4)

169.9 b (± 6.4)

a all phenolic composition means were adjusted for grape sugar content using covariate analysis; °B; c mg gallic acid equivalents/L; mg malvidin-3-glucoside equiva-lents/L; e mg (+)-catechin equivalents/L;f means taken over all vine structure treatments for a specific vintage and climatic region as described in Materials and Methods;g different letters in a group in a column denote significant differences (P < 0.05); h standard error of mean;' means taken over all climatic regions and cordon heights fora specific vintage.

(HPLC) of the wines, did not differ significantly between winesof different climatic regions for the 2002 vintage (Tables 5 & 6).The polymeric anthocyanin content (pH shift) of the 2003 wineswas significantly lower for the wines from region IV compared tothose of region III, while no significant differences betweenwines from different climatic regions were observed for themonomeric and total anthocyanin content (pH shift), as well asthe monomeric anthocyanin content (HPLC) for the 2003 vin-tage. The coloured polymer content (HPLC) was not affected byclimatic region for either of the 2002 and 2003 vintages. Duringboth 2002 and 2003, a decrease in some individual anthocyanincontents of the wines, namely delphinidin-3-Glc, petunidin-3-Glcand peonidin-3-Glc, was observed from the coolest to thewarmest climatic region, while the opposite trend was observedfor other anthocyanins, namely vitisin A in 2002, and malvidin-3-Glc-Ac and malvidin-3-Glc-Coum in 2003 (Table 6). The mal-vidin-3-Glc, delphinidin-3-Glc-Ac, petunidin-3-Glc-Ac andpeonidin-3-Glc-Ac contents of the wines, on the other hand, werenot affected by climatic region of either of the vintages.

The total flavonols, quercetin and the unknown flavonol weresignificantly more abundant in region II wines, compared toregion III and IV wines of the 2002 vintage (Table 7). The cli-matic regions had no significant effect on the flavonol content ofwines from different climatic regions during 2003. Quercetin-3-Glc was significantly less abundant in region III wines, compared

to region II and IV wines of the 2002 vintage, while quercetin-3-Rham content of region III wines was lower than that of region IIonly.

The climatic regions did not affect the phenolic acid content ofthe 2003 wines, but total phenolic acid content and some individ-ual phenolic acids of the 2002 wines were affected (Table 8).Region II gave wines with a higher total phenolic acid contentthan the other regions. These wines also contained significantlyhigher caftaric and coutaric acid contents. Wines produced fromregion III grapes had a higher gallic acid content than those fromregion IV grapes.

Trends for the flavan-3-ol content of wines from different cli-matic regions also differed for the three vintages investigated(Tables 5 & 8). In 2001 and 2002, the warmest region producedwine containing a lower total flavan-3-ol content (DAC) thanwines from the other regions. In the case of the 2003 wines, thetotal flavan-3-ol content (DAC) did not differ significantlybetween region II and III wines, but region III wines had a sig-nificantly higher total flavan-3-ol content (DAC) than region IVwines. The non-coloured polymer content of the 2002 wines wasnot affected by climatic region, while the 2003 wines from regionII had significantly less non-coloured polymers than the winesfrom region III. Climatic region only had an effect on the (+)-cat-echin and procyanidin B1 contents in 2002. (+)-Catechin and pro-cyanidin Bl concentrations were higher for wines from the



TABLE 6

Anthocyanin content3 of the 2002 and 2003 Pinotage wines.

2002: Climatic region6

Region II

Region HI

Region IV

2003: Climatic regione

Region II

Region IH

Region IV


Bush vines

Trellised vines

2003: Vine structure treatment*1

Bush vines

Trellised vines

Dp-3-GIc

20.98 af

(± 1.00)g

16.68 b(± 0.74)

14.11c(±0.82)

15.54 a(± 1.04)

14.48 a(± 1.20)

10.81 b(± 0.99)

15.73 b(± 0.76)

19.92 a(± 0.91)

14.50 a(± 1.01)

12.72 a(± 1.01)

Pt-3-GIc

26.99 a(± 0.83)

24.73 ab(± 1.01)

22.14 b(± 0.36)

23.35 a(± 1.16)

21.91 ab(± 1.35)

18.66 b(± 1.10)

22.96 b(±0.71)

25.64 a(± 0.92)

21.89 a(± 1.10)

20.72 a(± 1.10)

Pn-3-GIc

12.12 a(±0.85)

9.38 b(± 0.76)

8.30 b(±0.75)

6.89 a(±0.66)

5.89 ab(±0.77)

4.24 b(± 0.63)

10.32 a(± 0.76)

9.55 a(±0.73)

6.88 a(± 0.56)

4.47 b(± 0.56)

Mv-3-Glc

200.67 a(± 10.90)

217.55 a(± 9.79)

214.36 a(±9.66)

224.71 a(± 4.88)

229.15 a(± 5.60)

232.53 a(± 5.64)

197.01 b(±7.20)

224.71 a(± 6.96)

216.17 b(± 3.24)

242.27 a(± 4.45)

Monomeric anthocyanins

Dp-3-GIc-Acb

6.55 a(± 0.44)

6.03 a(± 0.40)

6.02 a(± 0.39)

4.91a(± 0.40)

4.73 a(± 0.47)

4.21a(± 0.38)

5.90 a(±0.33)

6.49 a(± 0.32)

4.88 a(± 0.34)

4.36 a(± 0.34)

VitisinAb

4.71b(± 0.82)

5.74 ab(± 0.74)

7.69 a(± 0.73)

4.41a(± 0.87)

6.50 a(± 1.01)

5.37 a(± 0.83)

6.62 a(± 0.65)

5.48 a(± 0.63)

5.55 a(± 0.74)

5.29 a(± 0.74)

Pt-3-Glc-Acb

6.45 a(± 0.43)

6.11a(± 0.39)

6.18 a(± 0.38)

6.14 a(± 0.92)

4.61a(± 0.34)

4.65 a(± 0.30)

6.02 a(± 0.32)

6.50 a(±0.31)

5.62 a(± 0.64)

4.65 a(± 0.25)

Pn-3-Glc-Acb

4.28 a(± 0.28)

4.30 a(± 0.29)

3.74 a(±0.18)

6.50 a(± 0.40)

5.78 a(± 0.46)

5.81a(± 0.38)

4.40 a(± 0.19)

3.74 b(± 0.20)

6.65 a(± 0.30)

5.41b(± 0.30)

Mv-3-Glc-Acb

44.17 a(±3.56)

48.67 a(± 3.20)

53.79 a(±3.16)

59.26 b(± 1.35)

63.01 b(± 1.61)

78.99 a(± 2.28)

44.62 b(± 2.57)

53.13 a(± 2.49)

63.32 b(± 1.53)

72.14 a(±2.34)

Mv-3-Glc-Coumb

19.22 a(± 1.53)

20.96 a(± 1.65)

21.71a(± 1-32)

18.19 b(±1.67)

20.72 ab(± 1.95)

25.46 a(±1.60)

16.58 b(± 0.67)

24.99 a(± 1.17)

17.89 b(± 1.28)

25.02 a(± 1.28)

Total

345.47 a(± 17.39)

359.93 a(± 15.63)

358.78 a(± 15.41)

370.49 a(±7.15)

375.79 a(± 9.43)

390.68 a(±9.55)

331.08 b(± 10.93)

378.37 a(± 10.57)

362.22 b(±5.61)

397.64 a(± 7.68)

• Colouredpolymers'1

6.96 a(± 0.96)

7.67 a(±0.87)

9.36 a(±0.85)

13.17 a(± 0.79)

15.08 a(±0.91)

13.93 a(±0.75)

7.29 a(± 0.70)

8.70 a(± 0.67)

12.86 b(±0.57)

15.26 a(±0.57)

a mg/L unless otherwise noted; most means were adjusted for grape sugar content using covariate analysis except for Dp-3-Glc, Pt-3-Glc, Pn-3-Glc-Ac and Mv-3-Glc-Coum contents in 2002 and Mv-3-Glc, Pt-3-Glc-Ac, Mv-3-Glc-Ac and total monomeric anthocyanin contents in 2003; mg corresponding anthocyanin-3-Glc equiva-lents/L;c sum of phenolic group content; d mg malvidin-3-Glc equivalents/L; e means taken over all vine structure treatments for a specific vintage and climatic region asdescribed in Materials and Methods;f different letters within a group in a column denote significant differences (P < 0.05); g standard error of mean; h means taken overall climatic regions and cordon heights for a specific vintage; Dp = delphinidin; Glc = glucoside; Glc-Ac = acetylglucoside; Glc-Coum = p-coumaroylglucoside; Pt = petu-nidin; Pn = peonidin; Mv = malvidin.

coolest region compared to wines from the warmest region in2002.

The total monomer content (HPLC) was affected only in 2002,with wines produced from the coolest region having a higher con-tent (Table 8).

Climatic region: Effect on antioxidant capacity

The TACM of the wines was affected by the climatic region foronly the 2001 and 2002 vintages (Table 9). Regions II and III pro-duced wines with significantly higher TACM values, compared tothat of region IV, for both the 2001 and 2002 vintages. No TAC-CAL or TACR data are available for the 2001 wines as the phenoliccontent of these wines was not analysed using HPLC. The TAC-CAL of the wines from region II was significantly higher than thatof regions III and IV during 2002, while no significant differencewas observed during 2003. The TACR comprised between 80 and90% of the TACM and followed similar trends. The phenolic acidand anthocyanin contents contributed the most to the TACCAL ofthe 2002 and 2003 wines (Fig. 4). The contributions of phenolicacids and flavonols to the TACCAL were higher for region II winescompared to wines from the other regions during 2002, while theTAC contribution from flavan-3-ols was higher for wines from

region II compared to wines from region IV. During 2003, theTACCAL contribution of flavonols of the region II wines was notsignificantly different from that of the region IV wines, but sig-nificantly higher than that of the region III wines. The TACCALcontributions of anthocyanins in 2002, and phenolic acids, flavan-3-ols and anthocyanins in 2003, were not affected by climaticregion.

Climatic region: Effect on objective colour parameters

The objective colour parameters of the wines were only affectedby climatic region for the 2001 and 2002 vintages, with winesfrom the 2001 vintage the most affected (Table 9). Wines fromregion IV had higher L* and lower C* and b* values than winefrom the other regions of the 2001 vintage. The a* values ofregion III wines were significantly higher than those of region IVwines, while h * values of region II wines were significantly high-er than those from the other regions for the 2001 vintage. In thecase of the 2002 wines, only C*, a* and b* values were affectedby climatic region. The C* and a* values of region II wines weresignificantly higher than wines from region III and IV, while theb* values of region II wines were significantly higher than regionIII wines. Wines from the 2003 vintage also showed a slightly



TABLE 7

Flavonol content3 of the 2002 and 2003 Pinotage wines.

Unknowncompounds'"

Q-3-Glc Q-3-Rham Myricetin Quercetin Kaempferol Total0

2002: Climatic region"1

Region II

Region III

Region IV

2003: Climatic regiond

Region II

Region III

Region IV


Bush vines

Trellised vines


Bush vines

Trellised vines

23.29 ae(± 1.89/

16.09 b (± 1.00)

18.31 b (± 1.39)

24.95 a (±1.99)

22.97 a (± 2.32)

25.50 a (±1.90)

14.82 a (±1.17)

11.57 b (±0.79)

14.53 a (± 0.52)

15.92 a ( l 1.58)

12.07 a (± 1.84)

15.18 a (± 1.50)

9.66 a (± 0.69)

7.69 b (± 0.62)

7.90 ab (± 0.61)

9.84 a (± 0.59)

8.33 a (± 0.69)

9.22 a (± 0.56)

2.91 a (± 0.71)

3.31 a (±0.27)

3.44 a (± 0.33)

data not showng

data not showng

data not shown8

6.44 a (± 0.53)

3.68 b (± 0.49)

3.54 b (± 0.34)

3.52 a (± 0.29)

3.39 a (± 0.33)

3.20 a (± 0.27)

data not shown8 60.73 a (± 4.13)

data not shown8 43.84 b (± 2.61)

data not shown8 48.97 b (± 2.55)

0.74 a (±0.11) 56.27 a (± 4.07)

0.62 a (±0.12) 48.46 a (± 4.74)

0.63 a (±0.10) 54.61 a (± 3.88)

17.73 a (±1.07) 14.57 a (± 0.59) 8.62 a (±0.54) 3.26 a (±0.28) 4.51 a (±0.45)

20.19 a (±1.41) 12.73 a (± 0.75) 8.22 a (±0.52) 3.25 a (±0.22) 4.24 a (±0.39)

data not shown8

data not shown850.95 a (± 2.70)

50.13 a (± 2.75)

25.45 a (±1.43) 16.05 a (± 1.29) 9.90 a (±0.47) data not shown8 3.73 a (±0.23) 0.75 a (±0.09) 56.95 a (± 3.30)

23.79 a (± 0.85) 12.73 a (± 1.29) 8.36 b (±0.47) data not shown8 3.01b (±0.23) 0.57 a (±0.09) 49.27 a (± 3.29)

a mg/L unless otherwise noted; most means were adjusted for grape sugar content using covariate analysis except for unknown flavonol, Q-3-Glc, myricetin, quercetin andtotal flavonol contents in 2002; b mg rutin equivalents/L; c sum of phenolic group content; d means taken over all vine structure treatments for a specific vintage or cli-matic region as described in Materials and Methods; e different letters within a group in a column denote significant differences (P < 0.05); f standard error of mean; g datanot shown due to large number of wines without detectable amounts of compound; h means taken over all climatic regions and cordon heights for a specific vintage;Glc = glucoside; Q = quercetin; Rham = rhamnoside.

TABLE 8

Phenolic acid, flavan-3-ol and polymer contents of the 2002 and 2003 Pinotage wines.


Region II

Region III

Region IV


Region II

Region IE

Region IV


Bush vines

Trellised vines


Bush vines

Trellised vines

Gallicacid

13.87 ab£(± 1.61)h

14.90 a(± 1.45)

10.12 b(± 1.43)

10.64 a(± 0.59)

12.44 a(± 1.26)

10.93 a(± 1.30)

15.49 a(± 1.08)

10.44 b(± 1.04)

13.29 a(± 1.06)

9.13 b(± 0.47)

Caftaricacid

209.45 a(±5.72)

171.49 b(± 8.03)

168.72 b(± 6.26)

176.40 a(± 5.88)

177.13 a(±7.12)

174.53 a(±4.15)

171.47 b(±5.97)

190.10 a(±6.37)

177.46 a(± 4.88)

174.30 a(± 4.20)

Phenolic acids

Caffeicacid

5.51a(±0.27)

5.68 a(±0.35)

5.61a(± 0.42)

0.99 a(±0.15)

0.78 a(±0.13)

0.76 a(±0.12)

5.91a(± 0.34)

5.30 a(±0.25)

0.93 a(±0.11)

0.75 a(±0.11)

Coutaricacidb

22.31 a(±0.73)

17.92 b(± 0.82)

16.24 b(± 0.64)

16.61 a(± 0.62)

16.16 a(± 0.58)

15.52 a(± 0.33)

17.49 b(±0.71)

19.40 a(±0.73)

16.35 a(± 0.44)

15.80 a(± 0.39)

p-Coumaricacid

1.80 a(±0.37)

2.11a(± 0.34)

2.21a(± 0.33)

1.20 a(±0.17)

1.50 a(±0.17)

1.51a(±0.17)

2.36 a(± 0.26)

1.72 a(± 0.25)

1.49 a(±0.16)

1.31a(±0.12)

TntnlclOUlI

252.37 a(±6.52)

211.59 b(± 8.01)

203.94 b(±7.07)

205.84 a(± 6.59)

208.00 a(±7.65)

203.26 a(± 4.41)

212.25 a(± 6.67)

227.13 a(±7.10)

209.51 a(±5.22)

201.29 a(± 4.64)

(+)•Catechin

26.78 a(± 1.58)

23.17 ab(± 1.42)

19.41 b(± 1.40)

9.28 a(± 0.44)

8.89 a(± 0.48)

8.69 a(± 0.42)

25.23 a(± 1.24)

21.01 b(± 1.20)

10.13 a(10.33)

7.70 b(± 0.27)

Flavan-3-oIs

ProcyanidinBl

37.83 a(±2.39)

32.00 ab(±2.15)

28.13 b(±2.12)

12.33 a(±0.57)

14.09 a(± 0.66)

12.61 a(± 0.54)

35.06 a(± 1.87)

30.25 a(± 1.80)

13.70 a(± 0.47)

12.31 b(± 0.47)

Non-colouredpolymers'1

116.97 a(± 10.21)

122.29 a(± 10.35)

119.66 a(±7.83)

111.44b(± 10.59)

144.92 a(± 12.31)

122.76 ab(± 10.09)

102.15 b(±6.88)

137.39 a(±6.79)

120.31 a(± 9.20)

132.43 a(±9.19)

Totalmonomers6

721.66 a(± 19.62)

668.87 b(± 19.42)

660.61 b(± 12.26)

656.63 a(± 11.80)

657.66 a(± 13.72)

671.66 a(± 11.24)

652.08 b(± 13.26)

707.95 a(± 13.43)

657.44 a(±9.55)

666.53 a(±9.55)

a mg/L unless otherwise noted; most means were adjusted for grape sugar content using covariate analysis except for caftaric, caffeic, coutaric and total phenolic acid con-tents in 2002 and 2003, non-coloured polymers and total monomers contents in 2002 and gallic acid, p-coumaric acid and (+)-catechin content in 2003; b mg p-coumaricacid equivalents/L;c sum of phenolic group content; d mg (+)-catechin equivalents/L; e sum of all quantified monomeric phenolic compounds;f means taken over all vinestructure treatments for a specific vintage or climatic region as described in Materials and Methods; g different letters within a group in a column denote significant dif-ferences (P < 0.05); h standard error of mean;' means taken over all climatic regions and cordon heights for a specific vintage.



TABLE 9

Antioxidant capacity and objective colour parameters of the 2001, 2002 and 2003 Pinotage wines.

2001: Climatic region"

Region II

Region III

Region IV

2002: Climatic region*

Region II

Region III

Region IV

2003: Climatic region1

Region II

Region III

Region IV

TAC Mb

12.77 ak (± 0.67)1

13.02 a (±0.47)

10.44 b (± 0.42)

16.11 a (±0.62)

15.17 a (± 0.46)

13.77 b (± 0.31)

13.32 a (± 0.50)

14.02 a (± 0.58)

12.69 a (± 0.47)

Antioxidant capacity8

TACCALC

na

na

na

2.26 a (± 0.05)

2.13 b (±0.04)

2.04 b (± 0.03)

1.95 a (±0.04)

1.98 a (± 0.04)

1.98 a (± 0.03)

TACRd

na

na

na

14.02 a (±0.61)

13.04 a (± 0.46)

11.87 b (±0.26)

11.37 a (±0.48)

12.04 a (± 0.46)

10.71 a (± 0.46)

c*e

60.85 a (± 0.76)

61.12 a (± 0.50)

58.41 b (± 0.52)

63.44 a (± 0.70)

61.02 b (±0.66)

61.24 b (±0.63)

61.55 a (± 0.87)

60.08 a (±1.02)

60.57 a (± 0.83)

Objective colour parameters

h*t

15.50 a (±0.61)

14.52 b (±0.42)

13.02 b (±0.38)

14.83 a (±0.71)

13.52 a (± 0.57)

14.02 a (± 0.57)

14.17 a (± 0.53)

13.40 a (± 0.62)

13.19 a (±0.51)

25.62 b (±1.85)

26.76 b (± 1.28)

32.74 a (±1.15)

30.89 a (± 1.73)

34.58 a (+1.62)

33.34 a (±1.55)

31.64 a (±1.33)

31.16 a (±1.55)

33.35 a (± 1.27)

fl*h

58.49 ab (± 0.65)

59.17 a (+0.47)

56.86 b (± 0.48)

61.23 a (+0.63)

59.26 b (± 0.58)

59.35 b (± 0.56)

59.63 a (±0.21)

59.32 a (+ 0.44)

58.97 a (+0.41)

16.66 a (± 0.72)

15.14 a (±0.51)

13.20 b (± 0.42)

16.34 a (±0.81)

14.36 b (± 0.64)

14.77 ab (± 0.65)

15.09 a (± 0.65)

14.01 a (± 0.75)

13.90 a (± 0.62)

2001: Vine structure treatment"1

Bush vines 12.44 a (± 0.52) na

Trellised vines 11.71 a (± 0.53) na

na 59.51 a (± 0.54) 14.51 a (±0.46) 27.82 a (± 1.42) 57.64 a (+0.48) 14.66 a (± 0.44)

na 60.25 a (± 0.48) 14.19 a (± 0.46) 28.93 a (± 1.44) 58.43 a (+0.43) 14.49 a (± 0.52)


Bush vines 15.41 a (± 0.45) 2.08 a (± 0.04) 13.50 a (± 0.41) 61.86 a (±0.61) 14.96 a (± 0.24) 31.06 b(± 1.26) 59.74 a (± 0.53) 15.98 a (± 0.28)

Trellised vines 14.32 a (±0.31) 2.17 a (±0.04) 12.18 b (±0.31) 61.93 a (± 0.58) 13.23 b (± 0.64) 34.81 a (± 1.19) 60.15 a (±0.50) 14.18 b (± 0.74)


Bush vines 14.16 a (±0.40) 1.99 a (±0.03) 12.17 a (±0.39) 61.31 a (±0.73) 14.28 a (± 0.43) 31.10 a (± 1.15) 59.42 a (+0.25) 15.13 a (±0.53)

Trellised vines 12.53 b (+0.40) 1.95 a (±0.03) 10.58 b (± 0.39) 60.16 a (± 0.73) 12.90 b (± 0.43) 33.00 a (± 1.15) 59.17 a (±0.40) 13.54 b (± 0.53)

a antioxidant capacity values for 2003 were adjusted for grape sugar content using covanate analysis; b total antioxidant capacity in rnM Trolox equivalents as measured;c total antioxidant capacity in mM Trolox equivalents as calculated from the content of monomeric phenolic compounds and their Trolox equivalent antioxidant capacity;d T A C R = T A C M - TACCAL; e chroma; f hue angle (°); g lightness; h red/green chromaticity;' yellow/blue chromaticity; J means taken over all vine structure treatments fora specific vintage or climatic region as described in Materials and Methods; k different letters within a group in a column denote significant differences (P < 0.05); ' stan-dard error of mean; m means taken over all climatic regions and cordon heights for a specific vintage; na = not available.

higher C* when produced from the cooler climate, although thedifference was not statistically significant.

Climatic region: Discriminant analysis

Canonical discriminant analysis was performed to attempt dis-crimination between the wines from different climatic regionswith regard to variables relating to phenolic composition.Forward stepwise variable selection was applied to obtain vari-ables with the highest discriminating power for climatic regionfor each of the 2002 and 2003 vintages. Sixteen and 18 variableswere selected for the 2002 and 2003 vintages, respectively (Figs 5& 6). Regions II and III wines can easily be discriminated fromregion IV wines by the first discriminant function in both vin-tages, while regions II and III wines are separated by the seconddiscriminant function with minor overlapping. More overlappingbetween regions II and III wines occurs during 2003. During2002, the caftaric acid, malvidin-3-Glc-Ac and coloured polymer(HPLC) contents had the highest positive correlations to the firstdiscriminant function, while the coutaric acid, p-coumaric acidand malvidin-3-Glc contents contributed greatly in the negativedirection of the first discriminant function (data not shown). The

• Phenolic acids

B Flavan-3-ols

O Flavonols

DAnthocyanins

Region III

Region IV

0.0 0.5 1.0 1.5 2.0 2.5

TACCAL contribution (mM Trolox equivalents)

FIGURE 4

Phenolic group contributions to the calculated total antioxidant capacity (TAC-CAL) of wines from different climatic regions (as described in Materials andMethods) [different letters for the contribution of a specific phenolic group in the

same year denote significant differences (P < 0.05)].



second discriminant function for the 2002 wines was mostly con-trolled by the caftaric acid and malvidin-3-Glc-Ac contents in thepositive direction and by the malvidin-3-Glc content in the nega-tive direction (data not shown). Among the variables contributingmost to the first discriminant function for the 2003 wines werethe positively-correlated delphinidin-3-Glc-Ac, malvidin-3-Glcand coutaric acid contents and the negatively-correlated mal-vidin-3-Glc-Ac and delphinidin-3-Glc contents (data not shown).The coutaric acid, (+)-catechin and delphinidin-3-Glc-Ac con-tents made the greatest positive contribution to the second dis-criminant function for the 2003 wines, while the greatest negativecontributions were made by the caftaric acid, procyanidin B1 andvitisin A contents (data not shown).

Vine structure: Effect on grape sugar content and phenoliccomposition

The grape sugar content did not differ significantly between vinestructure treatments for any of the vintages (Table 5).

Trunk height had a significant effect on the phenolic composi-tion of the wines in a small number of cases only (see Table 10).Bush vines with a trunk height of 20 cm produced wines with ahigher total phenol content than the 30-cm treatment for the 2002vintage. Individual phenolic composition was affected by trunkheight of wines produced in 2003, with the 20-cm bush vine treat-ment resulting in wines with significantly lower delphinidin-3-

Glc content and significantly higher caffeic and p-coumaric acidcontents compared to the 30-cm bush vine treatment. For the trel-lised vines, only the coloured polymer content (HPLC) of the2003 wines was affected, with a higher content for wines from the60-cm treatment compared to the 30-cm treatment. Due to the rel-atively minor influence of trunk height on the phenolic composi-tion of the wines, data for wines produced from bush and trellisedvines with averages taken over the different trunk height treat-ments are presented in Table 5 to 9.

The total phenol content was lower for wines from trellisedvines than from bush vines for all the vintages, although this trendwas only significant for the 2003 vintage (Table 5).

Vine structure treatment had little effect on the anthocyanincontent (pH shift) of the wines (Table 5). Only the polymericanthocyanin content (pH shift) of the 2002 wines was affected,with trellised vines resulting in wines with a lower content.Considering individual anthocyanins, vine structure treatment didnot affect the peonidin-3-Glc, delphinidin-3-Glc-Ac, vitisin Aand petunidin-3-Glc-Ac contents of the 2002 wines, and the del-phinidin-3-Glc, petunidin-3-Glc, delphinidin-3-Glc-Ac, vitisin Aand petunidin-3-Glc-Ac contents of the 2003 wines (Table 6).Apart from peonidin-3-Glc-Ac (2002 and 2003 wines) and peoni-din-3-Glc (2003 wines) that were increased in the wine by usinggrapes from bush vines, the contents of other anthocyanins,

" " " • • • *

FIGURE 5

Distribution of the 2002 Pinotage wines in the plane defined by the first two dis-criminant functions according to climatic regions (as described in Materials -andMethods) (variables selected = petunidin-3-Glc, peonidin-3-Glc, malvidin-3-Glc,vitisin A, malvidin-3-Glc-Ac, coloured polymer (HPLC), quercetin-3-Glc,kaempferol, isorhamnetin, gallic acid, caftaric acid, caffeic acid, coutaric acid, p-coumaric acid, (+)-catechin and non-coloured polymer contents, Glc = glucoside,

Glc-Ac = acetylglucoside).

1

FIGURE 6

Distribution of the 2003 Pinotage wines in the plane defined by the first two dis-criminant functions according to climatic regions (as described in Materials andMethods) (variables selected = delphinidin-3-Glc, peonidin-3-Glc, malvidin-3-Glc,delphinidin-3-Glc-Ac, vitisin A, peonidin-3-Glc-Ac, malvidin-3-Glc-Ac, mal-vidin-3-Glc-Coum, coloured polymer (HPLC), unknown flavonol, quercetin-3-Glc,quercetin-3-Rham, gallic acid, caftaric acid, caffeic acid, coutaric acid, (+)-cate-chin and procyanidin Bl contents, Glc = glucoside, Glc-Ac = acetylglucoside,

p-coumaroyl-glucoside, Rham = rhamnoside).

TABLE 10

Effect of cordon height on the phenolic composition3 of the 2002 and 2003 Pinotage wines.

2002 2003

Vine structure treatment Trunk height Total phenolsb Dp-3-GIc-Ac Coloured polymers0 Caffeic acid p-Coumaric acid

Bush vines

Trellised vines

20 cm

30 cm

30 cm

60 cm

1843.5 ad (± 60.7)e

1671.3 b (±82.9)

1709.6 ab (± 55.28)

12.83 b(± 1.12)15.59 a (± 0.94)11.64 b (±0.92)

12.00 b (± 0.54)13.43 b (± 0.67)13.87 b (± 0.76)

1.21 a (±0.16)

0.66 b (±0.12)

0.68 b (±0.13)

1.89 a (±0.24)

1.11b (±0.17)

1.36 b (±0.19)

1748.5 ab(± 52.18) 13.83 ab (± 1.24) 16.70 a (± 1.07) 0.83 ab (± 0.18) 1.26 b (±0.15)

mg/L unless otherwise noted; b mg gallic acid equivalents/L; c mg malvidin-3-Glc equivalents/L; d different letters in a column denote significant differences (P < 0.05);standard error of mean; Dp = delphinidin; Glc-Ac = acetylglucoside.



monomeric anthocyanins (HPLC) and coloured polymers(HPLC) (2003 only) were higher in trellised vine wines.

The flavonol content of the 2002 wines was not affected by thevine structure treatment, while only the quercetin-3-rham andquercetin contents of the 2003 wines from bush vines were sig-nificantly higher than those from trellised vines (Table 7).

The vine structure treatment did not affect the total phenolicacid, caffeic acid or p-coumaric acid content of wines, for eitherof the vintages (Table 8). The gallic acid content of wines pro-duced from bush vines was significantly higher than that of winesproduced from trellised vines for both vintages. The caftaric andcoutaric acid contents, on the other hand, were lower for winesfrom bush vines compared to trellised vines for the 2002 vintage,with no effect observed for the 2003 wines.

Bush vines resulted in wines with a higher total flavan-3-olcontent (DAC) than trellised vines for the 2003 vintage only(Table 5). When using HPLC analysis, this trend was confirmedfor the 2003 wines, and the same trend was also observed for the2002 wines (Table 8). In addition, bush vines gave wines withhigher (+)-catechin contents for both vintages and procyanidinBl contents for the 2003 vintage. On the other hand, the 2002wines produced from bush vines had a lower non-coloured poly-mer content compared to wines produced from trellised vines, butno effect was observed for the 2003 wines.

The total monomer content (HPLC) was higher for wines fromtrellised vines than from bush vines of the 2002 vintage, with noeffect observed for the 2003 vintage (Table 8).

Vine structure: Effect on antioxidant capacity

Trunk height did not affect the TACM, TACCAL or TACR of thewines (data not shown). Wines produced from bush vines hadhigher TACM values than those produced from trellised vines (allvintages), although this trend was only significant for the 2003wines (Table 9). The TACCAL, however, was not affected by thedifferent vine structure treatments for either the 2002 or 2003 vin-tages, but the TACR of bush vine wines was higher than that of

wines produced from trellised vines of both vintages. For the2002 wines, the lower anthocyanin contribution to the TACCAL ofthe bush vine wines was balanced out by the higher contributionof flavan-3-ol content, while for the 2003 wines the lower antho-cyanin contribution was cancelled out by the higher contributionsof phenolic acids, flavan-3-ols and flavonols (Fig. 7).

Vine structure: Effect on objective colour parameters

Trunk height did not significantly affect any of the objectivecolour parameters of the wines (data not shown). No significantdifferences in objective colour parameters between wines frombush and trellised vines were observed for the 2001 vintage (seeTable 9). The 2002 and 2003 wines, however, showed signifi-cantly higher h* and b* values for wines from bush vines, com-pared to wines from trellised vines, while the a* and C* valueswere not significantly affected by vine structure treatment. Forthe 2002 vintage, the L* value of wine from trellised vines wassignificantly higher than that of wines from bush vines.

Vine structure: Discriminant analysis

Canonical discriminant analysis with forward stepwise variableselection was also performed to attempt discrimination betweenthe wines produced from different vine structure treatments usingvariables relating to phenolic composition. Fifteen and 16 vari-ables were selected in the 2002 and 2003 vintage, respectively(Figs 8 & 9). Wines from vines with different trunk heights couldnot be discriminated for either of the two vintages. When the firsttwo discriminant functions arising in the canonical discriminantanalysis of the 2002 vintage are plotted for bush and trellised vinewines, there is very little overlapping. This indicates fairly gooddiscrimination between the vine structure treatments. For the firstdiscriminant function of the 2002 vintage data, the malvidin-3-Glc and gallic acid contents were highly positively correlated,while the malvidin-3-Glc-Coum, non-coloured polymer and del-phinidin-3-Glc-Ac contents were highly negatively correlated(data not shown). The second discriminant function was highlyinfluenced in the positive direction by the quercetin and petuni-

Trellised vines

• Phenolic acids

B Flavan-3-ols

D Flavonols

D Anthocyanins

6



din-3-Glc contents, while the delphinidin-3-Glc-Ac andkaempferol contents were the highest contributors in the negativedirection (data not shown). For data from the 2003 vintage, thediscrimination between wines from bush and trellised vines isless pronounced, with more overlapping. Variables with high cor-relation to the first discriminant function in the 2003 vintage werethe coloured polymer (HPLC) (positive), peonidin-3-Glc (nega-tive) and malvidin-3-Glc-Ac (negative) contents, while for thesecond discriminant function the malvidin-3-Glc-Coum and mal-vidin-3-Glc contents were the greatest contributors in the positiveand negative direction, respectively (data not shown).

DISCUSSION

Pinotage wines from the first vintage (2001) were analysed forphenolic composition using spectrophotometric assays, antioxi-dant capacity and objective colour parameters. Since this prelim-inary study showed that climatic region and vine structure treat-ment significantly affected wine properties, wines prepared dur-ing the subsequent two vintages were analysed more extensivelyusing HPLC analysis to identify trends for individual phenoliccompound content.

Effect of grape maturity

In this study it was attempted to harvest grapes within a windowof 2°B, i.e. between 24 and 26°B, as it may affect the composi-tion and characteristics of the resulting wines. Problems such aswidely dispersed vineyard sites and the dependence of ripenessdevelopment near the critical level on local daily weather phe-nomena, such as heatwaves and rain, hampered the harvesting ofgrapes at the same sugar content. Subsequently, -15% of treat-ments were harvested too early or too late, i.e. with a grape sugarcontent 26°B. The average grape sugar content didnot, however, differ significantly between the vintages or betweenclimatic regions and vine structure treatments in the respectivevintages. Covariance analysis with grape sugar content as covari-ate was performed, however, and the means for affected variableswere adjusted.

Vintage-related variations

Vintage-related variations in terms of phenolic composition andTAC are presumably due to variation in weather patterns for therespective years. Cooler night temperatures during the berry ripen-ing period in 2003 caused lower average February temperatures inthe respective climatic regions, compared to 2002 (unpublisheddata). This would explain the variations in the contribution ofmonomeric phenolic compounds to the TACM, represented byTACCAL, being lower for the 2003 wines compared to the 2002wines. This trend is especially due to lower contents of high poten-cy compounds, such as (+)-catechin, procyanidin Bl(De Beer etal, 2006), and most of the anthocyanin monoglucosides. This is inagreement with the findings of Mori et al. (2005), showing that theconcentration of anthocyanins in Pinot Noir berry skins wasdecreased by lower night temperatures. The TACR was also lowerfor the 2003 wines compared to the 2002 wines, due to changes inunknown compounds or oligomers with less than five subunits asthe non-coloured polymer content (polymers with five subunits orlarger) showed no significant differences between vintage wines.The lower TACM of the 2003 wines is therefore mostly due todecreased antioxidant capacity of monomeric phenolic com-pounds and small, unknown compounds.

,

FIGURE 9

Distribution of the 2003 Pinotage wines in the plane defined by the first two dis-criminant functions according to vine structure treatment (variables selected =peonidin-3-Glc, malvidin-3-Glc, vitisin A, petunidin-3-Glc-Ac, peonidin-3-Glc,malvidin-3-Glc-Ac, malvidin-3-Glc-Coum, coloured polymer (HPLC), quercetin-3-Glc, quercetin-3-Rham, myricetin, isorhamnetin, caffeic acid, p-coumaric acid,(+)-catechin and procyanidin B1 contents, Glc = glucoside, Glc-Ac = acetylglu-

coside, Glc-Coum = p-Coumaroyl-glucoside, Rham = rhamnoside).

The average wine hues for the different vintages were a similarmagenta-red hue, although hues of individual wines in each vin-tage ranged from red-magenta through magenta-red to pure red(data not shown).

The 2001 wines were darker (lower L*), with lower a* valuesthan the 2002 and 2003 wines (see Table 1). Their anthocyanincontent explains their darker colour, but not their lower a* valuesand unchanged C* values. This was unexpected, as the higheranthocyanin content should lead to increased C* and a* valuesand decreased L* values. However, inversion was observed withC* and a* values, especially at lower L* values, corresponding tovery dark wines. This phenomenon, previously reported for dark-coloured beverages (Eagerman et al, 1973), port (Bakker et al,1986), young red wines (Almela et al, 1995) and dark-colouredanthocyanin solutions (Gonnet, 1999), is related to the difficultyof photocells to adjust to low luminosity situations. The use ofcells with pathlength shorter than 5 mm would be advisable. L*values for the 2001 wines were generally lower than for the 2002wines, with more wines having L* values where inversionoccurred, explaining this discrepancy.

The higher colour saturation (higher C*) of the 2002 winescompared to the 2003 wines could possibly be due to higher con-tents of anthocyanin monoglucosides with high specific absorp-tivity, such as petunidin-3-Glc (Cabrita et al, 2000). Lower con-tents of some acylated anthocyanins, which generally have lowerabsorptivity (Giusti et al, 1999), should affect the colour satura-tion to a lesser extent. The higher phenolic acid and flavan-3-olcontents observed for the 2002 wines compared to the 2003 winescould also have increased the colour saturation due to anenhanced co-pigmentation effect with anthocyanins (Gonnet,1999). Other factors that can play a role are co-pigment to pig-ment ratios (Gonnet, 1999) and pH (Heredia et al, 1998).

Effect of climatic regionCooler ambient temperatures tend to favour accumulation ofanthocyanins in berry skins and the resulting wines (Bergqvist etal, 2001; Mateus et al, 2002; Miguel-Tabares etal, 2002; Spayd



et al, 2002) as also found in this study for Pinotage wines.Sunlight exposure, however, increases anthocyanin concentrationin grapes (Kliewer, 1970; Crippen & Morrison, 1986; Spayd etal, 2002). As sunlight exposure could differ between climaticregions, vineyard sites and individual canopies, this effect cannotbe separated from other climatic factors in the present study.

Mateus et al. (2001) reported that higher average temperaturesduring ripening produced berries and resulting Port wines withhigher flavan-3-ol content. The opposite trend was observed inthe present study during 2002.

Previous reports on flavonol accumulation in grape berriesfocussed on the effect of sunlight exposure (Haselgrove et al,2000; Downey et al, 2004), which does not necessarily coincidewith the effect of temperature. In the present study, no consistenteffects of climatic region on flavonol content were observed.

Previous studies did not include the effect of climate on thephenolic acids content. In the present study, different results wereobtained for the two vintages, suggesting that more vintages areheeded to clarify effects. Canonical discriminant analysis con-firmed the results of analysis of variance for the phenolic compo-sition of wines from different climatic regions.

The TACM values for wines from different climatic regions canbe explained by their total phenol contents. A relationshipbetween TAC and total phenol content of wines has previouslybeen shown (Landrault et al, 2001; De Beer et al, 2003). Thetrend for TACCAL of the 2002 wines could mainly be explained bya higher contribution by caftaric acid, (+)-catechin, procyanidinB1 and quercetin for region II wines, compared to wines from theother regions. These compounds have high antioxidant potency(De Beer et al, 2006). The caftaric acid content was much high-er for wines from the cooler climatic region, thus substantiallyincreasing its relative contribution to the TACCAL despite its rela-tively low antioxidant potency (De Beer et al, 2006). The antiox-idant contributions of both monomeric phenolic compounds(TACCAL) and unknown compounds (TACR) were higher forwines from cooler regions compared to warmer regions, as nosignificant differences in non-coloured polymer content wereobserved. The coloured polymer content (HPLC) was higher forregion IV wines compared to the wines from regions II and IIIand would thus negate some of the effect of the decreasing con-centrations of other compounds in these wines. During 2003,however, no significant difference in TACCAL was observedbetween wines from different climatic regions, due to the non-significant differences in contributions by phenolic acids, flavan-3-ols or anthocyanins. During both 2002 and 2003, the content ofsome anthocyanin monoglucosides increased in wines as the cli-matic region became progressively cooler, while the opposite wastrue for some acylated anthocyanins. For the 2002 vintage, thetotal contribution of anthocyanins to the TACCAL for the winesfrom the cooler climatic region was higher than for the winesfrom the warmer climatic region. Many phenolic compounds thatwere not measured and other compounds of low or high MW,such as proteins, peptides, polysaccharides and possibly others,could also contribute to the TAC of Pinotage wines, as discussedin De Beer et al. (2006).

The cooler climatic region produced wines that were generallydarker (lower L*) with a higher colour saturation (higher C*) and

a higher h*, namely a magenta-red hue closer to pure red, due toa higher b* compared to wines from the warmer regions during2001. However, in 2002 the region II wines had higher colour sat-uration (higher C*) due to higher a* and lower b* values, and nosignificant difference in lightness (L*). The average hue for the2002 wines from all the climatic regions was in the magenta-redrange. The higher L* and C* values observed for the 2001 winesfrom the cool climatic region is attributed to higher monomericanthocyanin contents. On the other hand, the higher C* for the2002 wines from the cooler region can be attributed to increasedanthocyanin monoglucoside contents. The higher co-pigment fac-tor contents, e.g. phenolic acids, flavonols and/or flavan-3-ols, forwines from cool regions, compared to warm region wines for the2001 and 2002 vintage would further explain the higher C* val-ues for these wines (Gonnet, 1999). On the other hand, the high-er co-pigment factor contents in the 2001 wines from region IIcaused a higher h* compared to wines from region III and IV,while the opposite was true for the 2002 wines. This apparent dis-crepancy is similar to both "blueing" (higher h*) and "yellowing"(lower /i*) effects for solutions containing cyanin and rutin, withincreasing co-pigment content, as described by Gonnet (1999).During 2003, no significant differences in total phenolic acid,total flavan-3-ol and monomeric anthocyanin contents for winesfrom different climatic regions were observed, while only differ-ences in some flavonols occurred. These results explain the lackof significant differences between objective colour parameters ofwines from different climatic regions. The average hue for the2003 wines from the different climatic regions was in the magen-ta-red range.

Effect of vine structure

Vine structure treatments had contrasting effects on the polymer-ic anthocyanin content (pH shift) and the coloured polymer con-tent (HPLC) for several reasons. The polymer peak in the HPLCchromatograms represents only polymers of five or more subunits(Peng et al, 2002), whereas polymeric anthocyanins of less thanfive subunits will be included in the pH shift assay measurement.Furthermore, the monomeric anthocyanins will contribute a smallamount to the polymeric pigment content due to residualabsorbance at pH 4.9 in the pH shift assay (Cabrita et al, 2000).It was previously reported that vine structure had no effect onberry skin anthocyanin content (Tamborra et al, 2003; Wolf etal, 2003). In contrast, the present study showed significant dif-ferences in the concentrations of several individual anthocyaninsin Pinotage wines, especially peonidin-3-Glc-Ac which was high-er for wines from bush vines and malvidin-3-Glc, malvidin-3-Glc-Ac and malvidin-3-Glc-Coum which were higher for winesfrom trellised vines.

Similarly, no significant differences in berry flavonol contentbetween berries from bush and trellised vines were shown byTamborra et al. (2003), but the present study showed significantdifferences in the concentrations of quercetin and quercetin-3-Rham, although only for the 2003 wines. Higher flavonol concen-trations for wines from bush vines should, however, not be due todifferences in sunlight exposure between vine structure treat-ments, as both bush and trellised vines had optimal canopy man-agement to ensure similar canopy densities in terms of leaf layers.

On the other hand, Tamborra et al. (2003) showed a similartrend for phenolic acid content, namely lower cis- and trans-caf-



taric acid and lower cis- and trans-coutaric acid in grape skins forgrapes from bush vines compared to trellised vines, as observedin the present study for the 2002 wines.

The effect of vine structure on the flavan-3-ol content of grapesor wines has not been reported to date. Wines from bush vineswere found to have higher (+)-catechin and procyanidin B1 con-centrations, but a lower non-coloured polymer content than winesfrom trellised vines. The results of the analysis of variance weresupported by the canonical discriminant analysis taking a numberof phenolic content parameters into account.

The differences in TACM for the vine structure treatments can beexplained by their difference in total phenol content as wasobserved for different climatic regions, with both parameters onlysignificant for the 2003 vintage. For the 2002 vintage, the loweranthocyanin contribution to the TACCAL of the bush vine wines,which is especially due to a much lower content of anthocyaninmonoglucosides and acylated malvidin derivatives, was balancedout by the higher contribution of the high antioxidant potency fla-van-3-ols, specifically (+)-catechin (De Beer et ai, 2006). In 2003the lower anthocyanin contribution, mostly due to substantiallylower contents of malvidin-3-Glc and its acylated derivatives, wascancelled out by higher contributions by phenolic acids, flavan-3-ols and flavonols, especially due to the higher contents of the highpotency antioxidant compounds, gallic acid, (+)-catechin and pro-cyanidin Bl (De Beer et al, 2006). The increased TACM of winesfrom bush vines compared to those from trellised vines in 2002and 2003 are thus mostly due to unknown compounds, especiallysince both the coloured and non-coloured polymer contents werelower for wines from bush vines.

Results for the objective colour parameters of the 2002 and2003 wines indicate that wines produced from bush vines weregenerally less magenta (higher h*) due to higher b* values thanthose produced from trellised vines. Higher h* and b* values forwines from bush vines for the 2002 vintage are attributed to theirhigher co-pigment content (gallic acid and (+)-catechin) andlower monomeric anthocyanin content than wines from trellisedvines, which changes the co-pigment to pigment ratio (Gonnet,1999). These results, as well as their higher polymeric antho-cyanin content (pH shift), explain their darker colour (lower L*).It did however not affect the a* values. Inversion could be a fac-tor in this case. In 2003, the higher h* and b* values for winesfrom bush vines compared to wines from trellised vines were dueto higher quercetin and quercetin-3-Rham contents. Higher gallicacid, flavan-3-ol and flavonol contents, by contributing to co-pig-mentation, cancelled out the negative effect of a lower monomer-ic anthocyanin content on the L* values of the 2003 wines frombush vines compared to the 2003 wines from trellised vines.

CONCLUSIONS

The phenolic composition, antioxidant capacity and objectivecolour parameters of Pinotage wines were significantly affectedby climatic region and vine structure treatments, although thetrunk height of the vine had few significant effects. In general, thewarmer climatic regions produced lighter coloured wines withlower TAC, mainly due to lower total phenol content. This trendcould be partly explained by the variation in phenolic composi-tion among wines from the different climatic regions, althoughunknown compounds are mostly responsible for differences in

TAC. Wines from bush vines were generally darker, with slightlyhigher TAC, than wines from trellised vines, although the latterwines had higher monomeric anthocyanin concentrations. Thiswas also due to increased total phenol content, although somephenolic compounds were present in lower quantities. Onceagain, unknown compounds contributed significantly to the dif-ferences in TAC between wines from different vine structuretreatments. Canonical discriminant analysis confirmed the obser-vations from analysis of variance for individual parameters byenabling discrimination between wines from different climaticregions and vine structure treatments (bush versus trellised vines)based on a large number of parameters. Cultivation of Pinotagebush vines in cooler climatic regions is recommended when ahigher TAC is a requirement. The effect of viticultural manipula-tions on the sensory quality of Pinotage wines is also importantand will be addressed in a future paper. Some vintage-relatedvariation was observed, which indicates that wines from morevintages need to be analysed in order to verify the resultsobtained in the present study.

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Climatic Region and Vine Structure: Effect on Pinotage Wine … · 2006. 12. 19. · Climatic Region and Vine Structure: Effect on Pinotage Wine Phenolic Composition, Total Antioxidant